When it comes to the Marauders, no one really likes Peter. Order members and Death Eaters alike. Why? Peter was a Death eater... Wasn't he? Not a true one, in my eyes.

Here's the Marauders. The first three, are in order of how much I like them, and below them, I will lista why I like them. Peter is #4, and I will lista some reasons not to like him, underneath.

1) Sirius Black
-He fights for what he believes in
-He was strong enough to pull away from his family, of blood-purity lovin' Blacks
-After TWELVES YEARS in Azkaban, he still came out determined to defeat Voldemort!
-He was not afraid to fight, if he could help out somewhere in a fight against DEs, he was there!
-He would do anything for those he loved; He risked the Dementors Curse when he moved closer Hogwarts to keep an eye on Harry in GoF.
-He also risked, and in turn gave, his life in OOTP when he heard Harry was in danger at the Department of Mysteries.
-He truly did care about Harry, when he only knew him for 2 years
-He WAS NOT the teen he was who bullied Snape anymore
-He stayed loyal to the Order!

2) Remus
-He's the logical one
-He was a fighter, through and through
-He was a werewolf, but he didn't turn to the dark side!
-He had to live with being a werewolf since he was a small kid
- He was such a good person, when other hombres lobo were truly monsters
-Twelve years, he went thinking he lost all his friends, and he lost them ALL in one day! That Halloween, he lost four friends. Three, he thought died (James, Lily & Peter). And one, he thought was a traitor, whom was being sent to Azkaban (Sirius). Imagine, learning all that in ONE day.
-He had Dumbledores trust
-He, like Sirius, fought every time he could
-He stayed loyal to the Order!

3) James
-We don't know much about him, but we KNOW he gave his life for his son, Harry!
-He was young, but he escaped Voldemort 3 times
-He loved Lily so much, that he changed for her
-If he had lived longer, I don't think he would try to pick a fight with Snape anymore
-He was only doing that to impress Lily
-He stayed loyal to the Order!

4) Peter
-What comes to mind, when I think of him? Traitor.
-Coward
-He switched to the Death Eater, after pledging allegiance to the Order
-Now, did he really want to do that? I think, it was out of fear.
-He was not loyal to his friends
-He did NOT stay loyal to the Order.

Now, look at the last reason for each. The first three have something in common, that the 4th will never. They're loyal. Order member o Death Eater, one quality tu must have is loyalty. That's my analysis.